Modèles numériques pour l'altitude des surfaces terrestres, glaciaires et océaniques. Comprend l'altitude terrestre, la bathymétrie et la ligne de rivage.
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The Elevation of a terrain surface, whether land based or bathymetric in nature described the Earth's morphology. The Elevation data theme includes digital elevation models for land, ice and ocean surfaces both for terrestrial elevation and bathymetry, as well as shorelines.
The main purpose of a Digital Elevation Model is to provide an elevation property with reference to a specified origin (vertical reference or datum). This property may be height (when the value is measured opposite to the gravity field of the Earth) or depth (when the value is measured in the direction of the gravity field). In line with existing technologies three spatial representation methods have been provided: grid, vector and triangulated irregular network (TIN). Regarding provision of data, the grid spatial representation type is mandatory for the description of land elevation, whereas the other ones are optional. Finally, either the grid or the vector spatial representation type is mandatory for the provision of data describing the bathymetry, whereas the other ones are optional.